Effect of metal powder size on the gas expansion behavior of 7075 Al alloy in a semisolid state

摘要

Gas expansion in a semisolid state at 903 K was quantitatively investigated from the viewpoint of the porosity, pore size and pore area for two kinds of 7075 Al alloy made of approx 25 and approx 355 mum powders. The pores were relatively uniformly formed and grown in a specimen made of the approx 25 mum powder. However, abnormally large pores of more than 500 mum in diameter were observed in the specimen made of the approx 355 mum powder, resulting from the nonuniform distribution of liquid phases. This points out the importance of a uniform distribution of liquid phases to reduce deviations in pore size.